1. Field of the Invention
This invention relates to housings and methods of assembling automotive ignition distributor components.
2. Prior Art
Hall effect devices produce an output voltage proportional to the magnetic flux passing through the device. Such Hall-effect sensors can be used in automotive systems to provide timing systems for automotive ignition distributor systems and for fuel injection systems. For example, a distributor shaft can be coupled to the engine and have an attached rotor member with a plurality of peripheral vane members extending outwardly. The vanes can be advantageously made of a high permeability ferrous material and successively pass through air gap in a magnetic circuit containing a Hall device positioned within the air gap. The flux which passes through the Hall device is shunted away from the Hall device by the vanes. This produces an electric output from the Hall effect device.
There are various known Hall effect sensor assemblies for use in automotive ignition distributor systems which are mounted in molded plastic holders. An air gap is provided for the passage of the vane through the holder and on each side of the air gap are molded portions for containing a magnetic and pole piece assembly and a circuit board assembly containing a Hall effect device and a flux concentrator. Since a molded holder has dimensions which will vary within certain tolerance limits, the relative positions of the circuit board, the concentrator, and the magnet and pole piece assembly with respect to each other are subject to variations. The method of assembling prior art components in the housing involves placing the components within predetermined molded recesses within the housing and fixing the components in place. Variation in the housing and component tolerances may provide for a variation in rotational position which would affect the timing provided by the Hall effect sensor.
A further problem exists when it is desired to use two Hall signal generator systems so that one can provide a signal for the ignition system and the other can provide a signal for the fuel injection system. It is often difficult to position the release point, or the firing point, of one Hall effect device with respect to the release point or firing point of the other Hall effect device. For example, it may be desired to position the two firing points exactly 90.degree. apart. The time required to adjust for accurate firepoint positioning can be prohibitive on a mass production basis. It would be desirable to have an apparatus and method for simple, accurate placement of the two Hall effect devices as well as allowing complete replacement of the Hall effect holder for retaining the original accuracy and not requiring any adjustment at the point of final assembly to the distributor. These are some of the problems this invention overcomes.
U.S. Pat. No. 4,185,600 issued to Brammer et al and U.S. Pat. No. 4,235,213 issued to Jellissen teach Hall effect distributors and the assembly of a single Hall effect device in the distributor. U.S. Pat. No. 4,373,486 issued to Nichols et al, U.S. Pat. No. 4,407,258 issued to Ruf and U.S. Pat. No. 4,459,968 issued to Brandt et al disclose the use of two Hall effect devices, but without discussion of positioning one Hall effect device with respect to another Hall effect device. In particular, Nichols et al addresses the use of one magnet to operate with two Hall effect devices and having two shutters attached to the common shaft passing between the Hall effect device and the magnet. Thus, this patent does not address the location of one Hall effect device firepoint with respect to the other Hall effect device firepoint. The patent to Ruf addresses the functioning of two Hall effect signal generators mounted within the distributor to control spark timing to fire each cylinder and to control fuel injection. The patent does not address how to locate or position the two Hall effect devices accurately with respect to each other. The patent to Brandt et al teaches the use of one Hall effect device on a crankshaft flywheel and another Hall effect device on a camshaft.